The correct answer is B) To release the raft from the cradle automatically as the ship sinks. The purpose of the hydrostatic release on an inflatable liferaft is to automatically release the raft from its storage cradle when the raft is submerged to a certain depth, typically around 4-6 meters. This ensures that the raft will float free from the sinking vessel and be available for occupants to board. The hydrostatic release is a critical safety feature that does not require any manual intervention, allowing the raft to deploy even if the crew is incapacitated. The other answer choices are incorrect - option A refers to the inflation mechanism, which is separate from the hydrostatic release, option C is about testing the raft's structural integrity, and option D is simply wrong.